Electronic switch and rectangular wave generator



w. A. KNOOP, JR, ET AL 2,365,476

ELECTRONIC SWITCH AND RECTANGULAR WAVE GENERATOR Filed May 1.1, 1945 l/zfiww' INVENTORS Jada HTTOIP/Vfy Patented Dec. 19, 1944 ELECTRONIC SWITCH AND RECTANGULAR WAVE GENERATOR Walter A. Knoop, J12. Packanack Lake, and Leonard F. Crnmer, Wayne, N. J., assignors to Allen B. Du Mont Laboratories, Inc., Passaic, N. J a corporation of Delaware Application May 11, 1943, Serial No. 486,518

6 Claims.

This invention relates to th generation of rectangular shaped currents or voltages that range in frequency from zero to hundreds of kilccycles per second. By this invention the frequency can be easily and quickly varied over a very wide range of frequencies and a plurality of signals of the same or diiierent lengths can be generated simultaneously.

The invention may be understood from th description in connection with the accompanying drawing, in which:

Fig. l is a side view shown slightly in perspective illustrating an embodiment of the invention;

Fig. 2 is an end view of the same; and

Fig. 3 is a similar view of a modification.

In the drawing, reference character l indicates a cathode-ray tube of the well known sort which is provided with a cathode 2, grid 3, first anode 4, second anode 5, and pairs of horizontal deflection plates 6 and vertical deflection plates 1 in the usual way.

The large end 8 of the tube is provided with fluorescent screen material t at th center on the inside. A plurality of areas or plates of conducting material H3 having radial sides and arcuate ends is provided on the inside around the screen 9. These plates may, for example. be carbonized metallic plates. or they may be made of other conducting material that can "be adhered to the inside surface of the end of the tube l. The corners It) may be about one -sixteenth of an inch apart.

The leads H are hermetically sealed through the wall of the tube. and they make contact separately with the respective plates ill. The number of these plates may he whatever is desired and may be the same or more or less than is indicated on the drawing. A resistance 92 is located in each lead and these leads may be grounded as shown. Only a few of the leads and resistances are shown in the drawing.

The operation is as follows: The cathode-ray beam is focused upon the fluorescent screen 9 whereby it can be readily ascertained whether it is of the desired intensity. A beam of one sixteenth of an inch in diameter of 200 milliamperes current at normal bias has been found to be sufficient for many purposes. The pairs of deflecting plates 6 and i may have sine waves of equal potentials and frequencies at 90 degrees difference in phase applied to them, thus providing a circular path on the screen 9 of a diameter dependent upon the amplitude of th signals applied to these plates, thus avoiding burning the screen 9 while this test is being made.

For generating the square wave impulses, the

potentials applied to the plates 6 and I are increased until the circular path or trace of the cathode-ray beam crosses or moves in a circular path across all of the plates or areas Hi. A sudden increase of current starts through each resistor i2 as the beam crosses its radially extending edge, the current remains constant while the beam is making its transit across the area It and suddenly drops to zero as it passes across the other radially extending edge of this area, thus producing a series of equally spaced rectangular impulses of the same height and length when the areas I0 are of the same size and are symmetrically disposed around the center screen 9.

By increasing the signals applied to the pairs of plates 6 and l, the beam is caused to cross the areas It nearer their outer ends, thus decreasing the duraticn of each rectangular impulse since the time to cross each one individually is decreased due to the increased velocity of the end of the beam.

When it is desired to keep the duration oi each rectangular pulse the same regardless of the intensity of the signals applied to the plates 6 and l, the sides of the areas it are made radiaLas shown in Fig. 3. The voltage developed across each external series resistance it connected to its collector plate 29 is used to change the grid bias of an amplifier channel individually, thus enabling any desired signal to he transmitted to an indicator.

The signals made to appear at the resistances it by this invention can be amplified in known ways and utilized when desired; such signals may, for example, he used for electronic switching; the frequency range can be expanded over present electronic switching; multi channel switching is provided for, which is limited only by the number of-collector elements IE on the end of the tube 8; rectangular Wave signals of adjustable periods and repetition rates can be produced; and the invention can be used for observing wave frequency transients.

What is claimed is:

i. In a device or. the character described, a cathode-ray tube having a series of separated circularly spaced radially extending conducting areas on the inside end of said tube, fluorescent screen material at a central area around which said conducting areas are located and separate electrical connections from said area to the outside of said tube, each oi said conducting areas having its side dimensions greater than its circumferential dimensions.

2 2,ses,47e

2. The device of claim 1, in which resistances 6. The device of claim 1. in which the side diare placed between the areas and mund. I mensions 0! said conducting areas lie along the 3. The device of claim 1, in which the areas radii of a circle whose center is at the middle of have parallel sides. the end of said tube and the end dimensions of 4. The device 0! claim 1, in which the areas 5 said conducting areas lie along two concentric have radially extending sides. circles.

5. The device oi claim 1, in which the side di- WALTER A. HOOP, Jl. mcnsions of said conducting areas are parallel to LIONARD 1''. exam each other and the end dimensions thereof lie alona two concentric circles. 10 v 

